A research study summitted in partial fulfilment of the requirements for the Degree of Master of Engineering, School of Environment, Resources and Development

Research Studies Project Report (M. Eng.) - Asian Institute of Technology, 1985

AIT Center is the only building in the campus to which the existing central chiller plant has to supply the chilled water for maintaining physical comfort in the building during the night. The cooling load profile of the building resulted from cooling load estimation shows the oversize capacity of the existing 340-ton chiller unit especially during the night. The maximum of cooling load of the building is estimated to be about 230 tons (807 KW) occurring at bout 1500 hr in April. By considering the cooling load profile, the feasible period for an energy conservation measure appears to occur between 1900-0700 hrs. The thermodynamic analysis, by both first law and second law, consistently indicates that poor efficiencies of the existing chiller operation occur during the night. The average coefficient of performance, COP and the average exegetic efficiency of the whole system are just about 2.19 and 15.5% respectively. After the simulation of a proposed separate small chiller set of two 90-ton units, both thermodynamic and various economic analyses indicate the feasibility of the recommended system operating between 1900-0700 hr. the COP and the exegetic efficiency of the proposed system would be 3.55 and 24.7% respectively. the proposed system will save the electricity bill by about 645,000 Baht per years. for AIT and the investment cost can be recovered within 4 years. The refrigeration cost of the proposed system would be 1.13 Baht per KHh of refrigeration lower than that of the existing system. The net present worth, benefit cost ratio, and internal rate of return of the proposed system also show the positive results which are about 874,000 Baht, 1.29, and 20% respectively.